Partitions in general, including walls, floors and ceilings in buildings, may have holes in them for passage of items such as vent pipes, drain pipes, plumbing pipes, gas pipes, electrical wiring, conduits to contain electrical telephone and computer wiring, optical fibre, air conditioning ducts, heating ducts and the like. One hole may accommodate one or several such items. Annular spaces between the hole and the item passing through the hole create passages through which heat and fire can spread, especially if a pipe collapses or burns under the influence of heat. It is therefore desired to provide means for filling or blocking these spaces to prevent the spread of heat and fire through the holes. There are devices and materials known for this purpose. These have the disadvantages as they are cumbersome to apply, require tools and skills for their installation, and may require use of metal frames and screws or grout or caulking for their permanent installation. They may require that a seal to prevent passage of heat and fire is formed at the moment of installation. Such devices and materials make reentry to repair or to retro-fit piping and cabling systems difficult. Furthermore, in many cases subsequent visual inspection does not readily reveal whether the device or material has been properly installed or not.
It is an object of the present invention to alleviate some or all of the above-mentioned disadvantages.
The present invention provides a device that comprises a material that intumesces on exposure to heat, a patch of an adhesive connected to one surface of the intumescent material and a liner that covers the adhesive and is readily detachable from the adhesive by means of a pull, to expose the adhesive.
In another aspect the invention provides a method of providing a fire stop in a space between a hole in a partition and an item passing through the hole, which method comprises wrapping around the item a device as defined above, sliding the device along the item into the hole and pulling on the pull tab to expose adhesive and anchor the device permanently on the item by means of the adhesive.
In the description of preferred embodiments that follows, for purposes of illustration reference is made to a pipe passing through a hole. It should be appreciated that the pipe is merely representative of items that may pass through a hole, and examples of such items are mentioned above.
When the device is in place in a hole and heat from fire is encountered, the intumescent material swells markedly, thereby blocking the hole and preventing passage of heat, flame, smoke and the like. Suitable intumescent materials include flexible fire barrier felts that are disclosed in U.S. Pat. No. 5,830,319, the disclosure of which is incorporated by reference. The felt comprises an organic polymeric binder, organic fibres having pendant hydroxyl groups, for example cellulosic fibres, a heat absorbing compound that is suitably an intumescent compound, for example intercalated graphite, mica, perlite, vermiculite, hydrated sodium silicate, and a phosphorus compound.
One such intumescent material that is suitable for use in the present invention is a flexible fire barrier felt that is available from 3M under the trade-mark Interam Ultra GS. It is available in strips about 2 inches wide and about_inch thick in any length. When exposed to temperatures of at least 300xc2x0 F. (149xc2x0 C.) it intumesces rapidly, expanding up to approximately 25 times its original volume. It turns into a hard char that impedes or prevents passage of heat, fire, smoke and gases. The material exerts substantial pressures on items in the hole so that it compresses piping and wiring materials, thus further effecting a seal of the hole against fire, heat, smoke and the like. It also releases chemically bound water that helps to slow temperature rise.
In one simple embodiment of the invention, suitable for use with small holes and small pipes, the patch of adhesive is present directly on a surface of a strip of an intumescent fire barrier felt. The liner is removed from the patch of adhesive, the felt is flexed to permit it to be pushed into the hole and the adhesive attaches either to the exterior surface of the pipe or the interior surface of the hole, where it is held permanently in place. In another simple embodiment the intumescent felt strip is contained in a coating of, for example, a plastic sheet, woven fabric or, preferably, aluminum foil and the adhesive patch is on the coating. The intumescent felt material and the adhesive are operatively connected to each other via the coating, although not in direct physical contact. The coating contains the intumescent material when it first encounters heat and intumesces, so that the expanded material remains contained in the hole and blocks the hole, rather than perhaps being blown around by a fire draught and leaving the hole unblocked. These embodiments are more suited for use with small pipes, up to about 1 inch nominal diameter, and small holes, up to about 1xc2xd inch nominal diameter. 
For use with pipes larger than 1 inch and holes larger than 1xc2xd inch it is preferred to enclose the intumescent material in a container. 
The container surrounding the intumescent material is preferably flexible and has a certain degree of strength. Suitable materials for the flexible container include plastics materials and mention is made of polyolefins, particularly polyethylene, which heat will melt and may assist in sealing. Another flexible container material that can be used is a metal foil, such as aluminum foil. Yet another material is a fabric, for instance woven fibres of polyamide, polyester, polyolefin, polyacrylate, glass or ceramic or the like. A preferred container, particularly for more stringent conditions, is composed of a thin aluminum sheet or foil attached to a fabric or fiber reinforcing material made of, for instance, polyamide, polyester, glass, ceramic or the like. Suitable materials include fabric net reinforced aluminum foils with polyethylene heat seal layer available from Alpha Associates, Inc., of Woodbridge, N.J., U.S.A particularly the foil available under the designation Alpha) Style 4413-VLS(trademark).
To make a device for use with pipes sizes of about 1xc2xd a inch nominal and greater, the flexible container, when laid flat, is normally elongate and in use is folded to bring one end into contact with the other to form an annulus. In a preferred embodiment the two ends are held in contact by some means. The particular means for holding the ends is not critical. Persons skilled in the art will be able to suggest many possible means for this purpose, for instance a clip or clamp, or tape, or Velcro. Preferred is an adhesive covered with a detachable liner, so that the annulus can be readily made simply by detaching the detachable liner and pressing the two ends of the container together to be held by the adhesive. The demands on this adhesive are not particularly stringent, and suitable adhesives are available from 3M under the designation Scotch(trademark) 467 HiPerformance Adhesive and 468 HiPerformance Adhesive.
A device of the invention can be made by taking a sheet of the flexible material that will form the container. The sheet should be of the approximate length required for the maximum length of the container when flat, plus, if necessary, an allowance for sealing at each end to enclose the intumescent material. It should be of a width sufficient to encompass both the width and the height of the unexpanded intumescent material, plus again, if necessary, an allowance for sealing along one edge. The material can then be folded over the unexpanded intumescent material and sealed along one side and both ends, to form the required enclosure. One suitable way of doing this is by heat sealing, although it is again clear that this could be done by many other means, for instance use of adhesive or even stitching. The flexible container should not be a tight fit over the intumescent material, so that when the intumescent material does swell some of that swelling is accommodated before the flexible container becomes stressed by the swelling. It is important that the flexible container contain the intumescent material as it first swells on encountering the heat, so that the intumescent material stays in place and is trapped in the hole, surrounding the pipe that passes through the hole. The container holds the swelling material for at least this brief initial period of time. Even if a seal bursts or the container subsequently tears the expansion of the intumescent material in the confined space will hold at least the bulk of the expanded material in place and form an effective fire stop.
In order to locate the device permanently around the pipe and in a hole that is to be blocked, use is made of the patch of adhesive that is on one exterior surface of the container. That adhesive can be on the surface that becomes the inner surface when the device is formed into an annulus. The installation of the device is not particularly critical, provided that it adheres to the pipe, as the seal is not formed on installation but is formed only when heat causes the intumescent material to intumesce. On installation the device is wrapped around a pipe to form an annulus, or collar, using the adhesive or other sealing means at either end of the container to form the annulus, then thrust into the hole. Once the device is in the desired location a pull tab, which attaches to or is integral with the liner on the adhesive patch and projects from the hole, is pulled to remove the liner from over the adhesive patch. During insertion of the device in a hole there is usually some degree of friction between the inner surface of the device and the pipe that tends to help in holding the device in place before the exposure of the adhesive patch to form the permanent bond. The adhesive then comes in contact with the pipe and the device is held permanently by the adhesive at the desired location. The pull tab and liner, which at its one end is permanently attached to the container, projects from the hole and serves as a flag or marker to indicate that the device is in place. At this stage, or at any subsequent inspection, the hole can readily be examined visually to see that the device is in place in the hole, as indicated by the flag. Adhesion between the strip of adhesive on the inner surface of the annulus and the outer surface of the pipe can also be checked, of course.
Also within the scope of the invention is a device similar to that described in the immediately preceding paragraph, but differing in having the adhesive patch on the surface that becomes the outer surface when the device is formed into an annulus. With this device the adhesive attaches to the inside of the hole, rather than the exterior of the pipe. One application of this device is in a partition wall composed of studs faced on both sides with gypsum wallboard. For effective fire-stopping it is necessary to use two fire stops, one in each piece of wallboard, or to insert a sleeve that extends through the two pieces of wallboard and spans the gap that is equal to the width of the studs. In this case one fire stop can be inserted in the sleeve, which is, for example, of PVC or of 24 or 28 gauge sheet metal. The device can be held in place by the adhesive patch adhering the outer surface of the device to the inner surface of the sleeve.
As stated above, with the device of the invention the seal to prevent passage of heat, smoke, flame, etc. is not formed on installation, but is formed on exposure to heat causing rapid expansion of the intumescent material. The rapidly expanding intumescent material occupies whatever space is available, so it accommodates awkward shapes with ease. For instance, sometimes in a hole there is a pipe in which there is an elbow or a coupling between two pipes of different diameter, or two or more small pipes passing through one hole. These create awkward shapes and present problems for fire stops composed of rigid material and designed to form a seal immediately on installation. They present no problem with the fire stop of the present invention, however, as the intumescent material expands into whatever shape of space is available to form the required seal.
The intention is that the adhesion between a surface of the fire stop device and the outer surface of the pipe, or the inner surface of the hole, as the case may be, shall be permanent, and shall therefore be able to withstand variations in temperature, exposure to conditions of moisture, lack of humidity, vibration, exposure to gases and any other condition which might tend to reduce or break the adhesion. The demands on this adhesive material are therefore greater than the demands on the material joining the two ends of the container to form an annulus. If the latter adhesion should fail this is of no effect, because the device is still retained in place. In contrast, the adhesive holding the device to the pipe must remain in place and should therefore have the capacity of adhering to materials that have low surface energy. Suitable adhesives are known, for instance, from U.S. Pat. Nos. 5,602,221; 5,616,670 and 5,654,387 the disclosures of which are incorporated herein by reference. One adhesive for this purpose is available from 3M under the trade-mark Scotch 300LSE HiStrength Adhesive. It should be borne in mind that fire stop devices of the same construction might be used on pipes made of many different materials, such as various plastic materials, including but not limited to cellular core PVC (ccPVC), PVC, crosslinked PVC (CPVC), fire resistant polypropylene (FRPP), PVDF, ccABS and ABS, steel, galvanized steel aluminum, copper or mild steel which may have an anticorrosive oil finish, or be painted, and the adhesive should attach permanently and firmly to any of these materials.
Pipes and conduits used in buildings tend to be of certain nominal sizes. There is some variation in external diameter, because diameters quoted are often internal diameters and different pipes for different purposes have different wall thicknesses. The outer diameters of pipes encountered in buildings are clustered in various fairly narrow dimensional ranges, however, and a device of appropriate size is made for each range.
Alternatively, or in addition to sizing devices with regard to the pipe size it is possible to size them with regard to the hole size.
Usually in construction a hole to accommodate a pipe passing through it is sized so that the diameter of the pipe is about 50 to 80% of the diameter of the hole. In this case one appropriately sized device of the invention is all that is needed to form a fire stop. In some instances, however, it is necessary to insert a fire stop where the hole is much larger than the pipe. This is the case particularly when retrofitting, when, say, a 3 inch pipe may have been removed from a hole and in the retrofit a 1 inch pipe is passed through the hole. In such a case it is possible to use two devices of the invention. Immediately around the 1 inch pipe is placed a device appropriately sized for 1 inch pipe, and around that there is placed a second, larger device of the invention. Alternatively the hole can be partially filled with some non-combustible material, for example mineral wool.
As stated above, after installation of the device the pull tab can serve as a flag. The flags can be coded to indicate the size of the device, for instance with different colours.